1. Field of the Invention
The present invention relates to a substrate processing apparatus for processing a substrate with the use of a process liquid. Particularly, it pertains to a substrate processing apparatus of a simplified structure, which is capable of decreasing an amount of a process liquid to be used, and of restraining change in temperature of the process liquid.
In addition, the present invention relates to a substrate processing method for processing a substrate with the use of a process liquid. Particularly, it pertains to a substrate processing method which is capable of decreasing an amount of a process liquid to be used, and of restraining change in temperature of the process liquid.
2. Description of Related Art
There has been conventionally known a substrate processing apparatus including a processing unit that holds one substrate and processes the substrate held by the processing unit, namely, a so-called single-wafer processing unit (e.g., JP11-319732A). In general, a plurality of processing units are incorporated in the substrate processing apparatus, so that substrates can be concurrently processed in the respective processing units.
One substrate held in the single-wafer processing unit is generally processed by supplying a process liquid thereto while the substrate is being rotated. According to such a single-wafer processing unit, one substrate can be uniformly processed by supplying a process liquid onto a surface of the substrate. In order to subject a substrate to various processes using various process liquids, two or more kinds of process liquids can be supplied to the processing unit. A process liquid, which has been used for processing a substrate in the processing unit, is collected for the sake of economy. The collected process liquid is again supplied into the processing unit through a collecting line, and the process liquid is used for processing the same or another substrate.
Generally, when a process liquid (more specifically, chemical liquid) has a higher temperature, reaction by the process liquid is activated so that processing of a substrate is accelerated. Thus, a process liquid, which has been heated and held at a high temperature, is sometimes used for processing a substrate. In addition, the collecting line is equipped with a heater or the like, in order that the temperature of the process liquid to be recycled is maintained to be constant.
However, when a substrate is processed in the single-wafer processing unit, it is impossible to completely prevent change in temperature of the process liquid throughout the process. For example, a temperature of the process liquid, which has been spun off at a high speed from the substrate that is being rotated, is lowered. Further, when a process is started, heat of the supplied process liquid of a high temperature is likely to be absorbed by respective parts of the processing unit. A supplying system and a collecting system of a process liquid are common to the plurality of processing units. Thus, after a process of a substrate is started in a certain processing unit, for example, lowering of temperature of the process liquid that is collected from the processing unit invites change in temperature of the process liquid which is to be supplied to another processing unit.
Furthermore, when a process liquid is supplied onto a substrate, the process liquid is spun off at a high speed from the substrate that is being rotated, and is dispersed in the processing unit. In addition, when a different kind of process liquid is supplied into each processing unit, some of the process liquid should be discarded in order to prevent the process liquids of different kinds from being mixed and supplied onto a substrate. Thus, it is impossible to collect all the process liquid that has been supplied into the processing unit.
Furthermore, in addition to a supply line for supplying a process liquid and the above-described collecting line, the processing unit includes a discarding line for discarding a process liquid from the processing unit, and an evacuating line for evacuating an atmosphere in the processing unit. In accordance with the kinds of process liquids to be used, some of the supply line, the collecting line, the discarding line, and the evacuating line have to be separately provided for each kind of the process liquid. Furthermore, these respective lines are connected to each other between the plurality of processing units. As a result, in the substrate processing apparatus including the plurality of single-wafer processing units, a structure of the pipe arrangement is significantly complicated, and thus control of the substrate processing apparatus is significantly complicated.